Re: rack and pinion advice

I have nice api stepper drivers, they pretty much seem comparable to
gekos. The steppers I got off of ebay quite some time ago. The
only info off the label is 3volts, and they have six wires with
encoders on the back. I think they should work if not I will be
shopping for others, anyways they were cheap.

Troy


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "balsaman_cnc"
<balsaman_cnc@y...> wrote:

> I would guess you need to reduce at least 10:1, to get the

required

> torgue to move the axis. Reduction will be required to get good
> resolution as well, as a 200 step stepper will move .015" per step
> if you use a 1" dia. gear.
>
> What sort of drive, steppers etc, will you be using?
>
> Eric
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Troy"
> <superscooby3000@y...> wrote:
> > I am designing a 4'x8'gantry router with rack and pinion on the

x

> > and y. Does anyone have any advice on wether I should gear down
> > nema 34 stepper motors with timing belts and pullys?
> >
> > I am thinking without gearing down I would get the fastest

rapids

> > and at cutting speed, and I think I would get the most torque
> > because the motor wouldn't have to run as fast to move the

gantry

> > (I was under the impression that the faster you ran a stepper
> motor
> > the less torque you get.) Am I correct in this thinking or am I
> > missing something?
> >
> > I was planning on using pullys and timing belts anyways figuring
> it
> > would be easier to upgrade to servos if I wanted to in the
> future.
> > I just cannot decide if I need a 1:1 ratio or something else.

If

> I
> > did need a different ratio does anyone have advice on what that
> > should be? I was figuring on using the smallest spur gear I

could

> > get, or do I need something with more teeth engaged.
> >
> >
> > Another question: I was planning on using 14deg 20pitch gears

and

> > rack because that seems to be the cheapest route at Mcmaster,

and

> it
> > seems mcmaster doesn't carry long lenghts of 20deg rack.
> > Does 20deg make much of a difference on smoothness and is it

worth

> > the extra expense? (and does someone have a better source for
> 20deg
> > rack?) How about gears and rack with helical teeth, I saw
> > somewhere on the net but can no longer find the site, is that
> worth
> > while?
> >
> > any other advice you rack and pinioners and give would be

greatly

> > appreciated.
> >
> > Troy